<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <script src="https://cdn.bootcdn.net/ajax/libs/jquery/1.12.4/jquery.js"></script>
    <title>Hello World</title>
    <style>
        div {
            width: 100px;
            height: 100px;
            border: 1px solid black;
        }
    </style>

</head>

<body>
    <div></div>
    <div class="box1"></div>
    <div id="box2"></div>
</body>
<script>
    //jquery的固定写法
    $(document).ready(function() {
        console.log("hello word");
    });
</script>

</html>